I'm assuming you mean a link to your RPG character?
That would go something like this:

1. Copy (Ctrl C) the url of your character's topic.

2. Click the 'URL' button on the button row up there. ^^^^^^
If you can't find it, write this: [url][/url]

3. Take the first url bracket and do this:
[url=paste the link to your character]_[/url]

4. In between the brackets write what you want the url to say.
[url=the link to your character]Whatever you want to say[/url]

5. If done correctly, it should turn out like this: Whatever you want to say